The design of conventional electronic devices often involves reducing unstable electric current leakage and generation and leaking of electromagnetic waves, to comply with the requirements of international safety certifications, and prevent users from being hurt by the leaking current and electromagnetic waves.
The general approach to meet this objective is to channel the leaking current to the ground or use a shielding means to prevent the leaking current and electromagnetic wave from infiltrating through the tolerance of a coupling mechanism (assembly interface) which bridges a coupling interface and a plugging mainboard (such as the mainboard of a blade server, a graphic card, or the like).
Refer to FIGS. 1A, 1B and 1C for the conventional coupling mechanisms to prevent electromagnetic waves from leaking. FIG. 1A shows a first coupling mechanism. FIG. 1B shows a second coupling mechanism. FIG. 1C illustrates assembly of the second coupling mechanism.
Referring to FIG. 1A, the first coupling mechanism uses metal to provide a shielding effect, to prevent leaking of electromagnetic waves. On the outside (which is coupled with a coupling interface of an electronic device) of the coupling mechanism 10, an annular spacer 12 made of metal is provided to be wedged between a gap, formed between the coupling interface (not shown in the drawing) of the electronic device and the coupling mechanism 10, to reduce leaking of electromagnetic waves.
As there is a tolerance in the product design, a gap is formed between the annular spacer 12 and the coupling interface. Hence leaking of electromagnetic waves cannot be totally prevented.
To remedy the aforesaid problem, the second coupling mechanism is developed, including a conductive foamed plastic, capable of shielding electromagnetic waves, to prevent leaking of electromagnetic waves as shown in FIG. 1B. The coupling mechanism 20 has an annular conductive foamed plastic 24 located between an annular spacer 22 and a latch side of the coupling interface, to fill the tolerance mentioned above.
Referring to FIG. 1C, for assembly, the coupling mechanism 20 is moved and latched on a coupling interface 30 of an electronic device (not shown in the drawing), and the conductive foamed plastic 24 is squeezed by the coupling interface 30 and the annular spacer 22 and deformed, so that a tight coupling is formed between the coupling mechanism 20 and the coupling interface 30, and the gap of tolerance is filled to shield the electromagnetic waves.
However, the second coupling mechanism mentioned above still has drawbacks. Because the coupling mechanism 20 that attaches to the annular conductive foamed plastics 24 should be formed in a size slightly larger than the coupling interface 30 to enable the annular conductive foamed plastic 24 to be squeezed, to achieve a compensation effect, when the coupling mechanism 20 is moved and latched on the coupling interface 30 (for assembly), the periphery of the annular conductive foamed plastic 24 is extended outside the coupling interface 30. Hence it is difficult to squeeze the annular conductive foamed plastic 24 into the coupling interface 30. As a result, interference occurs, and assembly cannot be done smoothly.
Moreover, adding the annular spacer and the annular conductive foamed plastic increases the cost of the coupling mechanism. Hence how to reduce the interference of the annular conductive foamed plastic during assembly and reduce the cost of the coupling mechanism are issues pending to be overcome.